运行ANSYS命令 时出现的问题

我的程序是
/BATCH
! /COM,ANSYS RELEASE 9.0A1 UP20050128 20:48:30 10/18/2012

/input,start90,ans,'C:\Program Files (x86)\Ansys Inc\v90\ANSYSED\apdl
\',,,,,,,,,,,,,,,,1
/PREP7
K,1,0,-1,1
K,2,0,1,1
K,3,0,1,-1
K,4,0,-1,-1
K,5,10,-1,1
K,6,10,1,1
K,7,10,1,-1
K,8,10,-1,-1
V,1,2,3,4,5,6,7,8
VPLOT
/VIEW,1,1,1,1
ET,1,SOLID45
MP,EX,1,200000
MP,NUXY,1,0.3
TYPE,1
MAT,1
ESIZE,0.5
VMESH,ALL
FINISH
/SOLU
NSEL,S,LOC,X,0
D,ALL,ALL,0
NSEL,S,LOC,Y,1
SF,ALL,PRES,100
NSEL,ALL
N1=NODE(10,0,0)
F,N1,MY,1
但是运行时，ANSYS会提示SPECIFIED FORCES FROM THE PREVIOUS F COMMAND WERE APPLIED ONLY TO THE SELECTED NODAL LOAD SET请问这是怎么回事